As more particularly discussed in the background considerations of the invention disclosed in the Vogelsonger U.S. Pat. No. 3,710,160, it is further highly desirable that a unitary brush spring have a length which provides a substantially constant firm conductive contact pressure without causing undue wear of an electrically conductive brush engaging the commutator in a universal fractional horsepower electric motor. For accomplishing these purposes, the springs are comparatively light and normally have a free length substantially exceeding the length of the brush holder and, if free to do so, would contact the commutator and not only be damaged but also cause other damage if and when the brush is worn down enough to drop out of position or make inadequate contact with the current carrying brush housing on the commutator.
Furthermore, the reduction of material and production costs and the ease and rapidity of assembly of the spring, brush and armature as a production time-saving consideration are of importance, including the installation of the brushes after the field and armature have been assembled.
In providing a new and improved graphite brush mounting assembly, the brush and spring are easily installed after the armature and brush carrier subassemblies have been mounted in the motor frame. Then, when the brushes are to be installed, they are inserted in place, followed by the springs which are then compressed and temporarily held in place while an end flap integrally formed with the brush housing is bent to hold the spring in compressed position in the brush housing.
A further object of the invention is to provide a simplified brush assembly which prevents the brush compression spring from coming into contact with the commutator after the brush has worn beyond its effectiveness or dropped out.